Evaluating the environmental dimension of material 2 efficiency strategies relating to the circular economy 3

Material efficiency is a key element of new thinking to address the challenges of reducing 12 impacts on the environment and of resource scarcity, whilst at the same time meeting service and 13 functionality demands on materials. Directly related to material efficiency is the concept of the 14 Circular Economy, which is based on the principle of optimising the utility embodied in materials 15 and products through the life cycle. Whilst steel, as a result of high recycling rates, is one of the most 16 ‘circular’ of all manufactured materials, significant opportunities for greater material efficiency 17 exist, which are yet to be widely implemented. In the field of Life Cycle Management, Life Cycle 18 Assessment (LCA) is commonly used to assess the environmental benefits of recovering and 19 recycling materials through the manufacturing supply chain and at end-of-life. As well as 20 containing information to calculate environmental impacts, LCA models also provide the flows of 21 materials through the product life cycle and can also be used to quantify material efficiency and the 22 circularity of a product system. Using an example taken from renewable energy generation, this 23 paper explores the correlation between product circularity and the environmental case for strategies 24 designed to improve material efficiency. An LCA-based methodology for accounting for the 25 recovery and re-use of materials from the supply chain, and at end-of-life, is used as the basis for 26 calculating the carbon footprint benefits of five material efficiency scenarios. Resulting carbon 27 footprints were then compared with a number of proposed material circularity indicators. Two 28 conclusions from this exercise were that i) LCA methodologies based around end-of-life approaches 29 are well placed for quantifying the environmental benefits of material efficiency and circular 30 economy strategies and ii) when applying indicators relating to the circularity of materials these 31 should also be supported by LCA studies. 32